It depends on whether you have ownership (or control) of the switch or not. If you do, then the easiest way is to 'span' the ports/vlans you want to sniff on to the port that your sensor is plugged in to. Spanning is not an industry-wide feature, I'm not sure if any switch manufacturers other than Cisco support a similar feature. Or, if the device you are sniffing on can understand, or at least strip, 802.1q tags, you can plug your sniffer into a trunk port. If you don't control the switch there are various ways to make other ports visible. Arp cache poisoning targeting the hosts or the routers works in some cases, as does fooling the switch into making multiple CAM entries for your port by changing your L2 address. There probably resource exhaustion attacks that will through a port (or blade?) in to a broadcast mode, but I've never seen one successfully executed. As with all things YYMV; I've noticed that different firmware/IOS versions can have a great effect on the effectiveness of all these techniques. Regards- Matthew B. Henniges Security Engineering Internet Support Services Merrill Lynch -----Original Message----- From: DrKimble@t-online.de [mailto:DrKimble@t-online.de] Sent: Wednesday, January 30, 2002 5:05 PM To: vuln-devat_private Subject: switch jamming hi guys, actually i have been reading the discussions on your board for quite a long time, but this is my first own posting - so please be fair on me ;-)) at the moment my boss is planning a firm which will take care of firm networks and so we discussed several topics. that's where my question starts: how can i sniff upon a switched network segment ? a read some articles about "switch jamming" and "port mirroring" but up to know i didn't learn anything special at all. ca some of your guys out there help me ? (i'm sure some of you can but are you willing, too ?) best regards, jan
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